A single-institution pre-post comparison of subcutaneous immunoglobulin replacement therapy in allogeneic haematopoietic cell transplantation recipients.

Immunoglobulin replacement therapy (IgRT) reduces the risk of infection in hypogammaglobulinaemia secondary to chronic lymphocytic leukaemia and multiple myeloma. However, the benefit of IgRT, especially subcutaneous IgRT (ScIgRT), has not been assessed in hypogammaglobulinaemia after allogeneic haematopoietic cell transplantation (allo-HCT). We performed a pre-post comparison of the clinical impact of ScIgRT after allo-HCT in a retrospective analysis of 209 patients who underwent allogeneic HCT at our institution from 2011 to 2019. Since ScIgRT became available at our institution in April 2017, we categorized patients treated from January 2011 to March 2017 as the Pre-ScIgRT group (n = 118) and those treated from April 2017 to December 2019 as the Post-ScIgRT group (n = 91). The 2-year overall survival rate was 65% in the Pre-ScIgRT group and 81% in the Post-ScIgRT group (p = 0.02). The cumulative incidence (CI) of non-relapse mortality at 2 years was 18% and 7% (p = 0.02). There were 78 infectious events in 44 patients in the Pre-ScIgRT group and 28 such events in 19 patients in the Post-ScIgRT group. The CI of the documented infection during the observation period was between 38% and 21% (p = 0.01). Our study suggests that ScIgRT may reduce infection rates and improve prognosis after allo-HCT.

Special AT-Rich Sequence-Binding Protein 1 Supports Survival and Maturation of Naive B Cells Stimulated by B Cell Receptors.

Epigenetic mechanisms underpin the elaborate activities of essential transcription factors in lymphocyte development. Special AT-rich sequence-binding protein 1 (SATB1) is a chromatin remodeler that orchestrates the spatial and temporal actions of transcription factors. Previous studies have revealed the significance of SATB1 in T cell lineage. However, whether and how SATB1 controls B cell lineage development is yet to be clarified. In this study, we show that SATB1 is an important factor during splenic B cell maturation. By analyzing SATB1/Tomato reporter mice, we determined the dynamic fluctuation of SATB1 expression in the B cell lineage. Although SATB1 expression decreased to minimal levels during B cell differentiation in the bone marrow, it resurged markedly in naive B cells in the spleen. The expression was dramatically downregulated upon Ag-induced activation. Splenic naive B cells were subdivided into two categories, namely SATB1high and SATB1-/low, according to their SATB1 expression levels. SATB1high naive B cells were less susceptible to death and greater proliferative than were SATB1-/low cells during incubation with an anti-IgM Ab. Additionally, SATB1high cells tended to induce the expression of MHC class II, CD86, and CD83. Accordingly, naive B cells from B lineage-specific SATB1 conditional knockout mice were more susceptible to apoptosis than that in the control group upon anti-IgM Ab stimulation in vitro. Furthermore, conditional knockout mice were less capable of producing Ag-specific B cells after immunization. Collectively, our findings suggest that SATB1 expression increases in naive B cells and plays an important role in their survival and maturation.

Autonomous TGFß signaling induces phenotypic variation in human acute myeloid leukemia.

Heterogeneity of leukemia stem cells (LSCs) is involved in their collective chemoresistance. To eradicate LSCs, it is necessary to understand the mechanisms underlying their heterogeneity. Here, we aimed to identify signals responsible for heterogeneity and variation of LSCs in human acute myeloid leukemia (AML). Monitoring expression levels of endothelial cell-selective adhesion molecule (ESAM), a hematopoietic stem cell-related marker, was useful to detect the plasticity of AML cells. While healthy human hematopoietic stem/progenitor cells robustly expressed ESAM, AML cells exhibited heterogeneous ESAM expression. Interestingly, ESAM- and ESAM+ leukemia cells obtained from AML patients were mutually interconvertible in culture. KG1a and CMK, human AML clones, also represented the heterogeneity in terms of ESAM expression. Single cell culture with ESAM- or ESAM+ AML clones recapitulated the phenotypic interconversion. The phenotypic alteration was regulated at the gene expression level, and RNA sequencing revealed activation of TGFß signaling in these cells. AML cells secreted TGFß1, which autonomously activated TGFß pathway and induced their phenotypic variation. Surprisingly, TGFß signaling blockade inhibited not only the variation but also the proliferation of AML cells. Therefore, autonomous activation of TGFß signaling underlies the LSC heterogeneity, which may be a promising therapeutic target for AML.

A case of severe oral mucosal GVHD induced by heterologous SARS-CoV-2 vaccination after cord blood transplantation.

Patients who have undergone hematopoietic cell transplantation (HCT) are at a higher risk of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection than the general population. Therefore, early vaccination is recommended for post-transplant patients. Although exacerbation of chronic graft-versus-host disease (cGVHD) after the initial vaccination has been reported, it is unknown whether severe cGVHD occurs when different RNA vaccines are combined. We treated a patient who developed severe oral mucosal cGVHD after receiving two different RNA vaccines. Visual inspection showed that the patient presented with typical mucocutaneous cGVHD, and cGVHD in this case responded well to low-dose steroids compared to common oral GVHD exacerbations. Histopathological findings revealed T cell, B cell, and conspicuous neutrophil infiltration. Multiple doses of SARS-Cov2 vaccination are required in post-transplant recipients. In conclusion, it is essential to obtain the vaccination history of allo-HSCT recipients with cGVHD exacerbation. Furthermore, reviewing the pathological findings may help treat patients with lower doses of steroids.

Gilteritinib in peritransplant period for relapsed or refractory FLT3-mutated acute myeloid leukemia: A case report of three patients.

Patients with relapsed or refractory acute myeloid leukemia (RR-AML) with mutations of FMS-like tyrosine kinase 3 (FLT3) have a poor prognosis even after allogeneic hematopoietic cell transplantation (allo-HCT). Multiple FLT3 inhibitors, including gilteritinib, have been developed and serve as treatment options for RR-AML. Here, we describe three cases of FLT3 mutated RR-AML that were successfully treated with gilteritinib administration before and after allo-HCT. Gilteritinib treatment before HCT was helpful in achieving remission. However, HCT often resulted in mild liver damage, and careful introduction of gilteritinib after HCT at a lower dose may be helpful for its safe usage. The three cases discussed had a successful clinical outcome in terms of disease control as well as the management of side effects associated with gilteritinib treatment.

Autoimmune-mediated thrombocytopenia after allogeneic hematopoietic stem cell transplantation: significance of detecting reticulated platelets and glycoprotein-specific platelet autoantibodies.

Autoimmune hematological disorders are rare complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Diagnosis of immune thrombocytopenia (ITP) is challenging, especially after allo-HSCT, because various complications such as graft-versus-host disease, disease relapse, viral infection, thrombotic microangiopathy, and drug side effects can also cause thrombocytopenia. Assessment of reticulated platelets (RP) and plasma thrombopoietin (TPO) levels may be useful to distinguish between ITP and hypoplastic thrombocytopenia. ITP is generally characterized by an increased percentage of RP, and a normal or slightly increased plasma TPO level. We now report three cases of thrombocytopenia after allo-HSCT. RP% was elevated in these patients, as it is in primary ITP. However, in contrast to primary ITP, plasma TPO levels were high in two of three patients. Anti-αIIbß3 and anti-GPIb/IX-specific direct IgG antibodies were detected as well, suggesting occurrence of immune-mediated platelet destruction in addition to bone marrow suppression in two patients. All three patients were successfully treated with corticosteroids and/or thrombopoietin receptor agonists (TPO-RAs). These results suggest that increased RP% and detection of glycoprotein-specific platelet autoantibodies are useful for the diagnosis of ITP after HSCT.

Modification of a loop sequence between alpha-helices 6 and 7 of virus capsid (CA) protein in a human immunodeficiency virus type 1 (HIV-1) derivative that has simian immunodeficiency virus (SIVmac239) vif and CA alpha-helices 4 and 5 loop improves replication in cynomolgus monkey cells.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) productively infects only humans and chimpanzees but not cynomolgus or rhesus monkeys while simian immunodeficiency virus isolated from macaque (SIVmac) readily establishes infection in those monkeys. Several HIV-1 and SIVmac chimeric viruses have been constructed in order to develop an animal model for HIV-1 infection. Construction of an HIV-1 derivative which contains sequences of a SIVmac239 loop between alpha-helices 4 and 5 (L4/5) of capsid protein (CA) and the entire SIVmac239 vif gene was previously reported. Although this chimeric virus could grow in cynomolgus monkey cells, it did so much more slowly than did SIVmac. It was also reported that intrinsic TRIM5alpha restricts the post-entry step of HIV-1 replication in rhesus and cynomolgus monkey cells, and we previously demonstrated that a single amino acid in a loop between alpha-helices 6 and 7 (L6/7) of HIV type 2 (HIV-2) CA determines the susceptibility of HIV-2 to cynomolgus monkey TRIM5alpha. RESULTS: In the study presented here, we replaced L6/7 of HIV-1 CA in addition to L4/5 and vif with the corresponding segments of SIVmac. The resultant HIV-1 derivatives showed enhanced replication capability in established T cell lines as well as in CD8+ cell-depleted primary peripheral blood mononuclear cells from cynomolgus monkey. Compared with the wild type HIV-1 particles, the viral particles produced from a chimeric HIV-1 genome with those two SIVmac loops were less able to saturate the intrinsic restriction in rhesus monkey cells. CONCLUSION: We have succeeded in making the replication of simian-tropic HIV-1 in cynomolgus monkey cells more efficient by introducing into HIV-1 the L6/7 CA loop from SIVmac. It would be of interest to determine whether HIV-1 derivatives with SIVmac CA L4/5 and L6/7 can establish infection of cynomolgus monkeys in vivo.

Endothelial Cell-Selective Adhesion Molecule Contributes to the Development of Definitive Hematopoiesis in the Fetal Liver.

Endothelial cell-selective adhesion molecule (ESAM) is a lifelong marker of hematopoietic stem cells (HSCs). Although we previously elucidated the functional importance of ESAM in HSCs in stress-induced hematopoiesis in adults, it is unclear how ESAM affects hematopoietic development during fetal life. To address this issue, we analyzed fetuses from conventional or conditional ESAM-knockout mice. Approximately half of ESAM-null fetuses died after mid-gestation due to anemia. RNA sequencing analyses revealed downregulation of adult-type globins and Alas2, a heme biosynthesis enzyme, in ESAM-null fetal livers. These abnormalities were attributed to malfunction of ESAM-null HSCs, which was demonstrated in culture and transplantation experiments. Although crosslinking ESAM directly influenced gene transcription in HSCs, observations in conditional ESAM-knockout fetuses revealed the critical involvement of ESAM expressed in endothelial cells in fetal lethality. Thus, we showed that ESAM had important roles in developing definitive hematopoiesis. Furthermore, we unveiled the importance of endothelial ESAM in this process.

Variable SATB1 Levels Regulate Hematopoietic Stem Cell Heterogeneity with Distinct Lineage Fate.

Hematopoietic stem cells (HSCs) comprise a heterogeneous population exhibiting self-renewal and differentiation capabilities; however, the mechanisms involved in maintaining this heterogeneity remain unclear. Here, we show that SATB1 is involved in regulating HSC heterogeneity. Results in conditional Satb1-knockout mice revealed that SATB1 was important for the self-renewal and lymphopoiesis of adult HSCs. Additionally, HSCs from Satb1/Tomato-knockin reporter mice were classified based on SATB1/Tomato intensity, with transplantation experiments revealing stronger differentiation toward the lymphocytic lineage along with high SATB1 levels, whereas SATB1- HSCs followed the myeloid lineage in agreement with genome-wide transcription and cell culture studies. Importantly, SATB1- and SATB1+ HSC populations were interconvertible upon transplantation, with SATB1+ HSCs showing higher reconstituting and lymphopoietic potentials in primary recipients relative to SATB1- HSCs, whereas both HSCs exhibited equally efficient reconstituted lympho-hematopoiesis in secondary recipients. These results suggest that SATB1 levels regulate the maintenance of HSC multipotency, with variations contributing to HSC heterogeneity.

Comparison of anti-viral activity of rhesus monkey and cynomolgus monkey TRIM5alphas against human immunodeficiency virus type 2 infection.

Human immunodeficiency virus type 2 (HIV-2) strains vary widely in their ability to grow in Old World monkey (OWM) cells. We previously evaluated several HIV-2 isolates for their sensitivity to cynomolgus monkey (CM) TRIM5alpha, an anti-HIV factor in OWM cells, and found that viruses carrying proline at the 120th position of the capsid protein were sensitive to CM TRIM5alpha, whereas those with either alanine or glutamine were resistant. In the study presented here, we tested these HIV-2 isolates for their sensitivity to rhesus monkey (Rh) TRIM5alpha and found that both CM TRIM5alpha-sensitive and -resistant viruses were restricted by Rh TRIM5alpha. The variable region 1 of the SPRY domain of Rh TRIM5alpha appeared to be the determinant of this difference. Furthermore, a mutagenesis study showed that three amino acid residues TFP at the 339th to 341st positions of Rh TRIM5alpha are important for restricting HIV-2 strains resistant to CM TRIM5alpha.

TRIM5alpha-independent anti-human immunodeficiency virus type 1 activity mediated by cyclophilin A in Old World monkey cells.

Cyclophilin A (CypA) is a peptidyl-prolyl isomerase that binds to the capsid protein of human immunodeficiency virus type 1 (HIV-1). TRIM5alpha is an antiretroviral factor influencing species-specific retroviral replication in Old World monkey (OWM) cells. In the study reported here, we investigated the role of CypA in anti-HIV-1 activity of OWM cells. Exogenous expression of CypA inhibited HIV-1 infection in OWM cells but not in human cells when the function of TRIM5alpha was suppressed by overexpression of dominant negative form of TRIM5alpha as well as by using RNA interference. This inhibitory action depended upon the interaction of the CypA moiety with HIV-1 capsid and disruption of CypA and capsid interaction by cyclosporine A enhanced the HIV-1 susceptibility of OWM cells even in the absence of functional TRIM5alpha. These results point to the presence of novel TRIM5alpha-independent anti-HIV-1 activity mediated by CypA in OWM cells.